Document Number: 70062 www.vishay.com
S11-0933-Rev. J, 16-May-11 11
This document is subject to change without notice.
THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT
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DG408, DG409
Vishay Siliconix
APPLICATION HINTS
Overvoltage Protection
A very convenient form of overvoltage protection consists of
adding two small signal diodes (1N4148, 1N914 type) in
series with the supply pins (see figure 10). This arrangement
effectively blocks the flow of reverse currents. It also floats
the supply pin above or below the normal V+ or V- value. In
this case the overvoltage signal actually becomes the power
supply of the IC. From the point of view of the chip, nothing
has changed, as long as the difference VS - (V-) does not
exceed + 44 V. The addition of these diodes will reduce the
analog signal range to 1 V below V+ and 1 V above V-, but it
preserves the low channel resistance and low leakage
characteristics.
Fig. 10 - Overvoltage Protection Using Blocking Diodes
Fig. 11
Vishay Siliconix maintains worldwide manufacturing capability. Products may be manufactured at one of several qualified locations. Reliability data for Silicon
Technology and Package Reliability represent a composite of all qualified locations. For related documents such as package/tape drawings, part marking, and
reliability data, see www.vishay.com/ppg?70062
.
1N4148
DG408
D
V-
V+
1N4148
S
X
V
g
EN
A
0
A
1
+ 15 V
(MUX On-Off Control)
Analog
Inputs
(Outputs)
Clock
In
NC
Enable In
Analog
Output
(Input)
+ 15 V - 15 V
DG408
D
EN
GND
DM7493
V+ V-
NC
GND
+ 15 V
Analog
Inputs
(Outputs)
Analog
Outputs
(Inputs)
+ 15 V - 15 V
DG409
GNDV+ V-
Differential
Differential
Clock
In
NC
GND
+ 15 V
NC
6
Reset Enable
J
K
CLK
J
K
CLK
CLEAR CLEAR
Q
S
5
S
7
S
6
S
8
S
1
S
3
S
2
S
4
S
1a
S
3a
S
2a
S
4a
S
1b
S
3b
S
2b
S
4b
D
a
D
b
A
0
A
1
A
2
B
IN
A
IN
r
01
r
02
Q
B
Q
C
Q
D
Q
A
1/2 MM74C73 1/2 MM74C73
Q
Q
Q
8-Channel Sequential Multiplexer/Demultiplexer
Differential 4-Channel Sequential Multiplexer/Demultiplexer